When the glamorous Elizabeth Chudleigh, Duchess of Kingston, Countess of Bristol, went on trial at Westminster Hall for bigamy in April 1776, the story drew more attention in society than the American War of Independence. A clandestine, candlelit wedding to the young heir to an earldom, a second marriage to a Duke, a lust for diamonds and an electrifying appearance at a masquerade ball in a diaphanous dress: no wonder the trial was a sensation. However,...